HIVEL2D

HIVEL2D is a free-surface, depth-averaged, two-dimensional model designed specifically for flow fields that contain supercritical and subcritical regimes as well as the transitions between the regimes. The model provides numerically stable solutions of advection-dominated flow fields containing shocks such as oblique standing waves and hydraulic jumps. HIVEL2D is designed specifically to simulate flow typical in high-velocity channels. The model is a finite element description of the two-dimensional shallow-water equations in conservative form. The model does not include Coriolis or wind effects as these are typically not important in high-velocity channels. HIVEL2D has been verified by comparing computed model results with laboratory data.

» Overview

Model Development

The basic steps to developing an application of HIVEL2D are as follows:

  • Generate the grid using SMS (Surfacewater Modeling System).
    • Number the grid intelligently.
    • Identify inflows and outflows.
  • Develop a hydrodynamic input file.
  • Develop a reasonable hot start file.
  • Run the model (probably several times). If necessary, refine the grid and interpolate a new hot start file.
  • View the output files in SMS.
  • Examine the solution for reasonableness.  

Guidelines

Remember the following general rules when generating the grid:

  • HIVEL2D uses linear elements. Therefore, when generating a HIVEL2D grid, use only four-node quadrilaterals and three-node triangles.
  • Keep the element aspect ratio less than 3:1 (the closer to 1:1, the better). The aspect ratio is the ratio of the longest element dimension to the shortest, i.e., the length-to-width ratio.
  • Use gradual transitions in element size. Generally, an element's area should not be greater than 1½ times its smallest neighbor.
  • Include at least five or six elements across a channel in the area of interest. If, for example, the channel has an island in the center, this resolution is needed on both sides of the island. Also, increase the resolution around grade breaks and wall transitions.

Once the grid generation is complete, be sure to renumber the grid using SMS renumber options. The best numbering scheme will give the smallest bandwidth. Normally, the nodes need to be numbered progressively across the narrowest dimension of the grid. This minimizes the bandwidth, which makes HIVEL2D run more efficiently.